This patent application claims priority based on a Japanese patent application, H11-258090 filed on Sep. 10, 1999, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an imaging apparatus, a drive mechanism and a method of driving the mechanism. More particularly, the present invention relates to a drive mechanism driving a lens and a diaphragm by a driving force supplied by a single drive source, a method of driving the mechanism, and an imaging apparatus including the drive mechanism.
2. Description of the Related Art
A drive mechanism that provides a driving force generated by a single drive source for driving a lens and a diaphragm is disclosed in Japanese Patent Application Publication No. H5-40883. This drive mechanism is provided by a motor that can supply a driving force capable of rotating two ways, a rotation member attached to a fixed portion in an optical lens device in a rotatable manner, and a transmitting means transmitting the rotation force from the motor to the rotation member and a lens barrel placed on a predetermined position inside the rotation member which holds a lens which is to be moved. The drive mechanism further includes: a converting means provided between the rotation member and the lens, converting the rotation motion to a liner motion by transmitting the rotation force of the rotation member to the lens barrel via a predetermined friction force to linearly move the lens barrel; a conventional diaphragm mechanism attached to the lens barrel and formed with a diaphragm drive member protruding outwardly, controlling a plurality of diaphragm blades formed inside the diaphragm mechanism to open and close; and a protruding portion protruding from the fixed portion, freely connected to the diaphragm drive member in the direction of the optical axis of the lens, the protruding portion being a fulcrum in the rotational direction.
However, the lens starts moving after an idle time caused by the diaphragm drive member, thus, the start of movement of the lens delays for the idle time with respect to the transmission of the driving force. Furthermore, as the rotational movement of the rotation member is converted to linear movement of the lens barrel, a shift of the optical axis caused by the rotation of the rotation member may result in inaccuracy of the focussing position.
Therefore, it is an object of the present invention to provide a drive mechanism driving a lens and a diaphragm by a driving force supplied by a single drive source, a method of driving the mechanism, and an imaging apparatus including the drive mechanism, which overcome the above issues in the related art. This object is achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
According to the first aspect of the present invention, a drive mechanism for moving a lens and adjusting a diaphragm using a driving force supplied by a single drive source, comprises a transmission mechanism capable of taking a first transmitting condition by which the driving force is transmitted for both adjusting the diaphragm and moving the lens, and a second transmitting condition by which the driving force is transmitted for either adjusting the diaphragm or moving the lens; wherein both the lens and the diaphragm are driven while the drive source is supplying the driving force to the transmission mechanism taking the first transmitting condition, and either the lens or the diaphragm is driven while the drive source is supplying the driving force to the transmission mechanism taking the second transmitting condition.
The transmission mechanism may include a slip mechanism provided between the drive source and at least one of the diaphragm and the lens, the slip mechanism transmitting the driving force to at least one of the diaphragm and the lens via a frictional force generated by the slip mechanism while the drive source is supplying the driving force to the transmission mechanism taking the first transmitting condition, and disconnecting transmission of the driving force to at least one of the diaphragm and the lens by slipping between the driving source and the at least one of the diaphragm and the lens while the drive source is supplying the driving force to the transmission mechanism taking the second transmitting condition.
The drive mechanism may further include a lens moving mechanism moving the lens along an optical axis of the lens, the drive source and the lens moving mechanism being connected without the slip mechanism therebetween, and the drive source and the diaphragm being connected via the slip mechanism, the slip mechanism disconnecting transmission of the driving force to the diaphragm by slipping between the driving source and the diaphragm and transmitting the driving force to the lens while the drive source is supplying the driving force to the transmission mechanism taking the second transmitting condition.
The diaphragm may comprise: a diaphragm plate adjusting luminous energy applied to the lens; and a position restrictor restricting a movement range of the diaphragm plate such that the diaphragm plate 50 can only move as necessary for adjusting the diaphragm, wherein the slip mechanism may be provided between the drive source and the diaphragm plate, and the slip mechanism disconnects transmission of the driving force to the diaphragm by slipping between the driving source and the diaphragm when the position restrictor restricts movement of the diaphragm plate.
The drive source may supply the driving force to either a forward driving direction or a backward driving direction, the lens moving mechanism may include a mechanism moving the lens along the optical axis thereof in accordance with the driving direction of the driving force, and the diaphragm mechanism may include a mechanism moving the diaphragm plate between a first position to a second position, both provided within the moving range in accordance with the driving direction of the driving force.
The lens moving mechanism may move the lens within a moving range including a first range necessary for moving the lens to focus on a subject, and a second range necessary for moving the lens in order for the diaphragm plate to move from the first position to the second position or from the second position to the first position of the lens.
The drive source may supply the driving force until the lens moves to the focussing position, further supplies the driving force, in a same direction, for a movement amount necessary for having the diaphragm plate move from the first position to the second position, or from the second position to the first position, and supplies the driving force, in an opposite direction from the same direction, for the movement amount necessary for changing, when the driving direction of the driving force for moving the lens to a focussing point where the lens is focused on the subject and the driving direction of the driving force for moving the diaphragm plate to a desired either the first position or the second position, are not same.
The drive source may supply the driving force until the lens moves to the focussing position, when the driving direction of the driving force for moving the lens to a focussing point where the lens is focused on the subject and the driving direction of the driving force for moving the diaphragm plate to desired either the first position or the second position, are same.
The diaphragm plate may be formed with a plurality of apertures each having different diameters, the diaphragm plate being moved by the drive source supplying the driving force until the lens moves to the focussing position, further supplying the driving force in a same direction for a movement amount necessary for having a desired aperture from among the plurality of apertures overlie a predetermined position, and supplying the driving force in an opposite direction from the same direction for the movement, such that light is applied to the lens through the desired aperture.
According to the second aspect of the present invention, a method of driving for moving a lens and adjusting a diaphragm by a driving force supplied by a single drive source, comprises: driving the lens and the diaphragm while the drive source is supplying the driving force to the transmission mechanism, taking a first transmitting condition by which the driving force is transmitted for both adjusting the diaphragm and moving the lens, and driving either the lens or the diaphragm while the drive source is supplying the driving force to the transmission mechanism taking the second transmitting condition, by which the driving force is transmitted for either adjusting the diaphragm or moving the lens.
According to the third aspect of the present invention, a method of driving for moving a lens to a focussing point where the lens is focussed on a subject and adjusting a diaphragm based on brightness of the subject, comprises: determining a condition for the diaphragm used for photographing the subject by detecting brightness of the subject, detecting the focussing position; and judging whether a first driving direction for moving the lens to the focussing position and a second driving direction for moving a diaphragm plate shutting out light to be applied to the lens to either a first position or a second position, are same; the method further comprising, when the driving directions are same, supplying the driving force for moving the lens to the focussing position the method further comprising, when the driving directions are not same, supplying the driving force until the lens moves to the focussing position, further supplying the driving force, in a same direction, for a movement amount necessary for having the diaphragm plate move from the first position to the second position, or from the second position to the first position, and supplying the driving force, in an opposite direction from the same direction, for the movement amount necessary for changing.
According to the fourth aspect of the present invention, An imaging apparatus for photographing a desired subject, comprising: an imaging unit forming an image of the subject; a lens imaging the subject on the imaging unit; a diaphragm adjusting luminous energy applied to the lens; and a drive mechanism moving the lens and adjusting the diaphragm by a driving force supplied from a drive source; wherein the drive mechanism comprising a transmission mechanism capable of taking a first transmitting condition by which the driving force is transmitted for both adjustment of the diaphragm and movement of the lens, and a second transmitting condition by which the driving force is transmitted for either adjustment of the diaphragm or movement of the lens; and both the lens and the diaphragm are driven while the drive source is supplying the driving force to the transmission mechanism taking the first transmitting condition, and either the lens or the diaphragm is driven while the driving source is supplying the driving force to the transmission mechanism taking the second transmitting condition.
The transmission mechanism may include a slip mechanism provided between the drive source and at least one of the diaphragm and the lens, the slip mechanism transmitting the driving force to at least one of the diaphragm and the lens via a frictional force generated by the slip mechanism while the drive source is supplying the driving force to the transmission mechanism taking the first transmitting condition, and disconnecting transmission of the driving force to at least one of the diaphragm and the lens by slipping between the driving source and the at least one of the diaphragm and the lens while the drive source is supplying the driving force to the transmission mechanism taking the second transmitting condition.
The drive mechanism may further include a lens moving mechanism moving the lens along an optical axis of the lens, the drive source and the lens moving mechanism being connected without the slip mechanism therebetween, and the drive source and the diaphragm being connected via the slip mechanism, the slip mechanism disconnecting transmission of the driving force to the diaphragm by slipping between the driving source and the diaphragm and transmitting the driving force to the lens while the driving source is supplying the driving force to the transmission mechanism taking the second transmitting condition.
The diaphragm may comprise: a diaphragm plate adjusting luminous energy applied to the lens; and a position restrictor restricting a movement range of the diaphragm plate such that the diaphragm plate 50 can only move as necessary for adjusting the diaphragm, wherein the slip mechanism may be provided between the drive source and the diaphragm plate, and the slip mechanism disconnects transmission of the driving force to the diaphragm by slipping between the driving source and the diaphragm when the position restrictor restricts movement of the diaphragm plate.
The drive source may supply the driving force in either a forward driving direction or a backward driving direction, the lens moving mechanism may include a mechanism moving the lens along the optical axis thereof in accordance with the driving direction of the driving force, and the diaphragm mechanism includes a mechanism moving the diaphragm plate between a first position to a second position, both provided within the moving range in accordance with the driving direction of the driving force.
The lens moving mechanism may move the lens within a moving range including a first range necessary for moving the lens to focus on a subject, and a second range necessary for moving the lens in order for the diaphragm plate to move from the first position to the second position or from the second position to the first position of the lens.
The drive source may supply the driving force until the lens moves to the focussing position, further supplies the driving force, in a same direction for an amount necessary for having the diaphragm plate move from the first position to the second position, or from the second position to the first position, and supplies the driving force in an opposite direction from the same direction for the amount necessary for changing, when the driving direction of the driving force for moving the lens to a focussing point where the lens is focused on the subject and the driving direction of the driving force for moving the diaphragm plate to desired either of the first position or the second position, are not same.
The drive source may supply the driving force until the lens moves to the focussing position, when the driving direction of the driving force for moving the lens to a focussing point where the lens is focused on the subject and the driving direction of the driving force for moving the diaphragm plate to desired either of the first position or the second position, are same.
The imaging unit may generate image data by converting the image of the subject into electric signals, the imaging apparatus further comprises a memory unit storing the image data.
This summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a sub-combination of the above described features. The above and other features and advantages of the present invention will become more apparent from the following description of embodiments taken in conjunction with the accompanying drawings.